Harry Caines sails his yacht into the small port of Wrelling. He can see the Custom House on the quay where he's taking up his new appointment as surveyor - the boss. He has yet to meet his team, but he believes the innovations and efficiency he is determined to bring about will not be popular with them. A real challenge - and perhaps a little more.
Harry Caines has a ruffled and unsettled team. The validity of his methods has yet to be proved. Time will tell, but right now there's word that Krugerrands are changing hands at a local casino. Caines suspects smuggling, but how to prove it. And what's worse - Tom Gibbons is implicated.
Caines asks Alyson to join the Road Fuel Testing Unit for a few days. So instead of the Custom-House long room, it's field and farmyard and getting to grips with members of the farming community. A celebration gives Caines a chance to relax with his team.
Caines and his team look into the complexities of the ice-cream trade, where skirmishes between two local firms seem about to explode into open warfare. An invitation to Harry Caines takes him into the home of a French businessman who Calvin suspects is up to no good.
Harry Caines decides to take the ferry to France and join the day trippers off for their bargains and duty free. An encounter with an ex-Army officer makes him wonder if the military mind is being put to something other than a day's sail across the Channel.
Caines's team are much concerned with the EEC regulations on carcasses, railway lines and a car. All seems set fair - but there is turbulence in the air which will affect everyone at Wrelling Custom-House.
A young girl disobeys her father, takes her sickly dog ashore from their yacht and loses it. Subsequent events suggest the dog may be rabid. The girl's heartbreak unlocks - for a moment - Caines's personal and tragic memories.
When Calvin has evidence that Charles Thieron is in possession of an unregistered and valuable gerfalcon, Caines confronts the Frenchman at his home. And he suspects that Thieron has more to hide than a bird.
Caines is concerned about certain members of his staff who are undergoing personal crises. Nigel receives a tip-off about a ship and its cargo, which Calvin thinks important enough to warrant immediate investigation.
Caines and his team are at Wembley cheering on Alyson in the show-jumping competition. Meanwhile, at Wrelling, Thieron's plans reach their climax with Annie playing a pivotal role. It's a long way from Wembley to Wrelling. When Calvin arrives home, will Annie be waiting for him?